JP2007530809A - Amylose starch product as a sizing agent for textile yarns - Google Patents

Abstract

  The present invention relates to the use of chemically unmodified amylose-type starch products as sizing agents for sizing natural and / or synthetic yarns. The present invention also relates to a method for sizing natural and / or synthetic yarns using a chemically modified amylose-type starch product as a sizing agent.

Description

  The present invention relates to the use of natural, chemically unmodified amylose type starch as a sizing agent for natural and / or synthetic textile yarns and blended yarns, and to fabrics using these starch products. The present invention relates to a method for sizing a yarn. The present invention further provides the use of chemically modified amylose-type starch as a sizing agent for natural and / or synthetic textile yarns and blended yarns, and using chemically modified amylose-type starch products. The present invention relates to a method for sizing textile yarn.

  A woven fabric is a two-dimensional object composed of fibers in a form in which yarns intersect at right angles (warp and weft), and is produced using a shed forming method. Each weft is subjected to pressure only for a short time when it is arranged at a predetermined position, whereas the warp is repeatedly subjected to pressure each time the weft is inserted and the hook is changed. The warp is subjected to pressure in such a manner that the yarn and metal rub against each other when the weft is pushed with reed, and is subjected to pressure when the heel is changed, and further subjected to pressure by a process of repeatedly stretching. Warp yarns are usually unable to withstand these extreme pressures and therefore must be applied without a protective coating, i.e. a sizing agent, that adheres to the fiber and forms a wear-resistant, resilient coating. Must not. Together with the short fiber spun yarn, the sizing agent plays the role of creating a yarn that can withstand the friction process that occurs during weaving. The protruding fibers adhere to the main body of the yarn so that adjacent warp yarns are not entangled or entangled. It is not very important that the overall tensile strength of the yarn is increased by about 20%, and it is very important to increase the strength at the weakest point.

  The sizing agent must adhere strongly to the fiber and its coating properties should be largely independent of climatic conditions, particularly atmospheric humidity, and should not be affected by fiber finishing and sizing additives. The presence of the sizing agent should not reduce the warp elongation.

  After the dough is woven, the role of the sizing agent is complete. Sizing agents usually have an adverse effect on the subsequent finishing process and must be completely removed. A sizing agent that is soluble in cold water is easy to remove, but starch products that are insoluble in cold water require preliminary enzymatic or oxidative degradation prior to the desizing step. Removal of the sizing agent can cause wastewater treatment problems specific to the final processing plant.

Many classes of chemicals are used as sizing agents. These substances are divided into two main groups.
1) High molecular natural products and their derivatives: starch and starch derivatives, carboxymethylcellulose, galactomannan, and tamarind powder derivatives
2) Synthetic polymer: polyvinyl alcohol, polymethacrylate, polyester condensate, and polyvinyl compound.

  The development of synthetic fibers and weaving technology has facilitated the development of synthetic sizing agents.

  The sizing agent to be used must meet a variety of requirements, for example, good penetrability, sufficient adhesion, excellent film forming properties, and the ability to form a resilient sizing film. Suitable sizing agents impart desirable properties to the sized spun yarn, such as high resistance to fraying (abrasion resistance), high weaving efficiency, and good wash-off properties of woven textile products. .

  About 70% of worldwide sizing agent consumption is starch and starch derivatives.

  Thus, starch and its derivatives are the most important type of sizing agent in terms of total consumption. This is because it is inexpensive, has a good sizing effect, and is available all over the world. The main raw material component of these types of sizing materials is a naturally occurring starch, ie a polysaccharide based on α-D-glucopyranose. Starch is not a single chemical, but is composed of two structurally different polymers: amylose and amylopectin. Amylose consists of a chain of glucose units linked by α-1,4-glucoside bonds, whereas amylopectin additionally contains α-1,6-glucoside bonds that lead to polymer chain branching (JA Radley : Starch and its Derivatives, Chapmann & Hall, London 1968; MW Rutenberg in RL Davidson (ed): Handbook of Water-Soluble Gums and Resins, McGraw-Hill, New York 1980, Chapter 22; J. BeMiller in RL Whistler, JN BeMiller (eds): Industrial Gums, Academic Press, San Diego 1993, p. 579; see G. Tegge: Staerke und Staerkederivate, Behr's Verlag, Hamburg 1984).

Amylopectin is the main component of starch and constitutes 73-86% of the total depending on the type of starch. The degree of polymerization of amylopectin is about 6,000 to 10 ⁶ glucose units, the degree of polymerization of amylose is about 100 to 1000 glucose units.

  The most important sizing agents are potato starch, corn starch, and tapioca starch. Wheat starch, rice starch, and sago starch are also used. The uniqueness of these starches depends on the amylose / amylopectin ratio, the degree of polymerization of these two components, and the size and microstructure of the starch granules. These parameters determine the swelling and solution properties and also the properties of the coating.

  Natural starch is insoluble in cold water because of the hydrogen bonds that tie parallel polymer chains. Starch becomes a “solution” upon heating. The starch granules first absorb water until swell is maximized. Above a certain temperature, known as the gelatinization temperature, specific for each type of starch, the starch granules burst and form a gel. After the viscosity has increased to a maximum, as the solubilized polymer molecules disperse, asymptotically decreases to an extreme value. Complete solubilization of the individual molecules of the starch granules occurs only above 100 ° C. Viscosity values are important in gluing because they have a significant effect on the amount of liquid absorbed.

  In the stored state, as the temperature is lowered, the starch paste solidifies into a separated state of thick water. Such aging is caused by the loss of hydrated water and the stretching of molecular chains, the chains are aligned in parallel, and hydrogen bonds are formed between adjacent chains (Tegge, 1984). Such aging has a deleterious effect on the sizing agent, leading to poor shelf life, thin film formation, deposit formation on the rollers, and poor adhesion. Thus, native starch is increasingly being replaced by starch derivatives.

（I）(1,6)-α-D分岐点を含む、アミロペクチンの代表的な構造。

（II）直鎖状アミロースの代表的構造 For example, natural potato starch consists of about 80% amylopectin (I) and 20% amylose (II).

(I) Representative structure of amylopectin, including (1,6) -α-D branch point.

(II) Typical structure of linear amylose

  Both polymers are present in the granules, but they are insoluble in water at room temperature. When the starch suspension is heated, the hydrogen bonds between the amylopectin chains and the amylose chains are weakened and eventually replaced by interaction with water molecules (hydrogen bonds). From about 61 ° C., the starch granules begin to swell and water molecules penetrate into the starch. Amylopectin has a stable viscosity in solution, but amylose has a strong tendency to gel. During this gel formation, amylose forms a double helix, which then aggregates to form a three-dimensional network.

  The use of various chemically modified starch products as sizing agents for textile yarns is a book of OB Wurzburg (ed.): Modified Starches: Properties and Uses CRC Press Inc. Boca Raton, Florida, Explained extensively by KW Kirby; Textile Industry, 1986, pp. 229-252. Referenced as chemically modified starches are starches modified with acids, oxidized starches, cross-linked starches, starch ethers and starch esters. As a starting material for modification, various types of starch such as corn starch, potato starch, tapioca starch and wheat starch can be used.

  It is well known that starch is useful for cotton fiber sizing and various other industrial purposes. In recent years, many synthetic fibers have become available, making it difficult to find relatively inexpensive sizing compositions suitable for sizing such various fibers, including cotton and synthetic fiber blends. In particular, it has become difficult to provide a low-cost sizing composition suitable for blending polyester fibers and cotton. In a typical method, the fibers are sized in the state of yarn or spun yarn before weaving. The sized yarn or spun yarn is then woven into a fabric, after which the sizing material is removed by washing with water containing detergent or by enzymatic treatment. A satisfactory sizing composition is a composition that provides adequate lubricity and resistance during weaving and at the same time can be easily removed thereafter.

  All modified starches that have lost their original properties are referred to as starch derivatives. These include thin-boiling starches, dextrins, starch esters and starch ethers.

  Thin-boiling starch is produced by acid hydrolysis or oxidative degradation in aqueous suspension, and dextrin is usually made by depolymerization by heating in the presence of acid. It can be gelatinized at low temperatures to give a low viscosity solution and dissolve in high concentration. Furthermore, it is easy to produce a liquid with a predetermined viscosity, and the susceptibility to aging is considerably reduced.

  The starch esters mainly used as sizing substances are phosphoric acid esters (phosphate starch) and acetic acid esters (acetyl starch). These starch derivatives are usually not only esterified, but also depolymerized, giving a lower liquid viscosity and resulting in reduced aging. In general, they give a better sizing effect than thin-boiling starch.

  The three most important types of starch ethers are hydroxyethyl starch, hydroxypropyl starch, and carboxymethyl, which are produced by the reaction of starch with ethylene oxide, propylene oxide, and chloroacetic acid or sodium chloroacetate, respectively, in the presence of caustic soda. It is starch. The degree of substitution of these starch derivatives is generally about 0.1 or less. Due to its ionic properties, sodium carboxymethyl starch dissolves in cold water and does not require desizing by an enzyme. Starch ether also provides a better sizing effect than a simply depolymerized starch derivative.

  The mechanical properties of coatings formed from solutions of starch or starch derivatives depend on the degree of hydration (which depends on the relative humidity in the weaving mill's atmosphere), as well as the ratio of amylose to amylopectin and the type of modified starch .

  The main uses of starch and starch derivatives are for sizing pure cotton yarn and blended spun yarn of cotton and other fibers. For these yarns a number of sizing agents are used which consist exclusively of or based on starch or starch derivatives. Starch and its derivatives adhere relatively strongly to cotton (J. Trauter, M. Laupichler, Melliand Textilber. 57 (1976) 375, 443, 545, 615, 713, 797, 875, 979; 58 (1977) 23, 111. See J. Trauter, H. Bauer, B. Ruess, M. Laupichler, Textilbetrieb (Wuerzburg), 96 (1978) 46; J. Trauter, TPI Text. Prax. Int. 44 (1989) 1297) . Cotton yarns woven by high-speed looms or spun yarns obtained by blending synthetic fibers at a high rate must be glued with a sizing agent further containing carboxymethylcellulose, polyvinyl alcohol, or polymethacrylate in order to improve the sizing effect. Starch is detected by blue coloration with iodine and this reaction is also used to semi-quantitatively measure the content of residual glue. (p. Wurster, g. Schmidt, Melliand Textilber 68 (1987) 581).

  It is an object of the present invention to provide a chemically unmodified amylose-type starch-based sizing agent that provides highly preferred sizing properties, weaving properties of sized yarns, and wash-off properties of woven fabrics. is there.

  It is also an object of the present invention to provide a sizing agent in which the amylose type starch is chemically modified.

  According to the present invention, the above object is achieved by using an amylose-type starch having an amylose content of 50% or more as a sizing agent.

  An amylose-type potato starch produced by a transgenic potato plant as described in Example 1 and having an amylose content of about 70% is formulated as described in Example 2 and as described in Example 3. Tested as a sizing agent. In addition, the desizing properties were analyzed, see Example 3.

  Compared to conventional potato starch, a formulation using amylose-type starch having an amylose content of about 70%, obtained from a genetically modified potato plant produced as described in Example 1, is more Reflects on achieving high wear resistance as well as better desizing properties, showing significant improvement in sizing performance. Compared to the best commercially available reference samples that were already chemically modified and optimized, comparable properties were obtained with chemically unmodified amylose-type starch.

  The term “high amylose starch” refers to any starch or starch fraction containing about 50% or more amylose by weight. Examples are “Nepol” amylose (amylose fraction of corn starch); “Superlose” (amylose fraction of potato starch); “Amylomaize” or “Amylon” (high amylose corn starch containing about 54% amylose); and Amylomaize VII (high amylose corn starch containing about 73.3% amylose). Amylomaize VIII having an amylose content of about 85% can also be used. The starch may be of any origin, for example from corn, wheat, potato, waxy corn, tapioca, sago or rice.

  In sizing textile fibers, a typical sizing composition consists of 100 pounds of amphoteric starch prepared according to the present invention, preferably 5 pounds of petroleum wax, mixed with 100 gallons of water, and then up to the gelatinization temperature. It can be prepared by heating. The yarn or spun yarn to be sized, such as a yarn or spun yarn comprising 65% polyester fiber (polyethylene glycol terephthalate) and 35% cotton fiber, is sized by passing it through the composition. When using this sizing composition, the number of fabric yarns woven during the loom change can be increased.

  After weaving, the sizing material can be removed by treatment with enzymes in the usual way or by washing with detergent water.

  The compositions of the present invention can also be used in other applications, such as textile finishing, textile and paper dyeing, paper sizing, and the application of pigments or paints to fabrics and paper.

  Sizing of 65% polyethylene glycol terephthalate, 35% combed cotton yarn, rayon, or other synthetic fibers, or blended yarns with natural fibers such as but not limited to cotton, wool It can be carried out by using an amylose-type starch having an amylose content of 50% or more as the sizing agent of the invention.

  Being linear, amylose has the ability to form flexible coatings with superior functionality for sizing of spun yarn. It is important to prevent gelation in this process because gelation results in an insoluble coating and shrinkage due to crystallization. Therefore, amylose can be replaced with hydroxyethyl-, hydroxypropyl-, or carboxymethyl groups to produce an amorphous and highly soluble coating, or amylose can be mixed with polymethacrylate glue and heated normally Prevent aging after the procedure.

  Preferably, the object can be achieved according to the invention by using chemically unmodified or modified amylose type potato starch as a sizing agent for natural and / or synthetic textile yarns. found. Below, the amylose type potato starch is briefly characterized.

  Potato starch granules isolated from potato tubers usually contain about 20% amylose and 80% amylopectin (wt% based on dry matter). However, over the past 10 years, genetically modified potato tubers from amylose exceeding 50% by weight (based on dry matter), preferably amylose exceeding 70% by weight, most preferably amylose exceeding 90% by weight Efforts to breed potatoes that form composed starch grains have been successfully achieved.

  Various enzymes have catalytic activity in the formation of starch granules in plants. Among these enzymes, starch granule-bound starch synthase (GBSS) is involved in the production of amylose. GBSS enzyme synthesis depends on the activity of the gene encoding the GBSS enzyme. Loss or inhibition of the expression of specific genes for amylopectin biosynthesis, starch branching enzyme 1 (SBE1) and starch branching enzyme 2 (SBE2), can result in complete loss or inhibition of amylopectin biosynthesis, for example in potato plants. Bring. Such gene removal can preferably be achieved by genetic recombination of potato plant material.

  Loss or suppression of SBE1 and SBE2 gene expression in potato plants, especially tubers, can also be achieved by using antisense technology, see Example 1. Methods for genetic modification of potato are described in patent applications WO92 / 11375, WO 97/20040, WO 92/14827, WO 95/26407 and WO 96/34968, and U.S. Pat.Nos. 5,856,467, 6,169,226, 6,469,231, 6,215,042, 6,570,066 and 6,103,893.

  It has been shown that by applying genetic modification, it is possible to breed and grow potatoes whose starch granules contain little or substantially no amylopectin.

  The term amylose-type potato starch as used herein means potato starch granules isolated from potato tubers, said starch granules having an amylose content of 50% or more by weight based on the dry substance. It is understood.

  Chemically modified amylose-type starch is herein referred to as amylose-type starch obtained by chemically modifying amylose-type starch by acid modification, oxidation, esterification, etherification, graft polymerization and / or crosslinking. It is understood to mean a starch product. Amylose-type starch can be physically modified (eg, by roller drying, extrusion, or hydrothermal treatment) or enzymatic modification before, during, or after chemical modification. Methods for preparing various chemically modified starches are described in the book of O.B. Wurzburg, Modified Starches: Properties and Uses; CRC Press Inc. Boca Raton, Florida, 1986. These methods can also be used to prepare chemically modified amylose-type potato starch used according to the present invention as a sizing agent.

  An aqueous solution of amylose-type starch as a sizing agent, also called a sizing bath or sizing glue, can be made in a conventional manner, for example in an open or closed boiling machine. Treatment of textile yarn with an aqueous solution of the chemically modified amylose-type potato starch product of the present invention can be carried out by conventional methods for sizing the yarn. For example, the yarn can be continuously passed through a solution of sizing agent, or the solution of sizing agent can be applied by spraying or using a roller. After passing through the sizing glue, the layer of yarn can be squeezed, for example, between two rollers. Thereafter, the squeezed yarn is dried on a heated cylinder or with warm air.

  Chemically modified amylose type starch has proven very suitable as a sizing agent for textile yarns. Yarns sized according to the invention are sufficiently resistant to mechanical influences (high shear resistance) in that they are covered with a strong, elastic and smooth coating. In textile factories, excellent results have been obtained with these yarns (high weaving efficiency).

  As mentioned above, the present invention relates to a method for sizing textile yarns. In this context, the term yarn is understood in the most general sense herein and is taken to include any cotton yarn or cotton staple yarn in the textile industry. Such yarns consist of unbroken natural cotton yarns or cotton fibers and / or semi-synthetic cotton polyester blends, which may or may not be twisted.

  The invention is further illustrated by the examples in the following examples. According to the examples, several properties were investigated on the sized yarn.

  In sizing textile fibers, a typical sizing composition consists of 100 pounds of amphoteric starch prepared according to the present invention, preferably 5 pounds of petroleum wax and mixed with 100 gallons of water before the gelatinization temperature. Can be prepared by heating up to. A yarn or spun yarn to be sized, such as a yarn or spun yarn containing 65% polyester fiber (polyethylene glycol terephthalate) and 35% cotton fiber, is sized by passing it through the composition.

Another sizing agent can be prepared by adding a neutralized (eg, with ammonia or sodium hydroxide) polymethacrylate-based emulsion polymer to a starch-containing sizing formulation. The preferred copolymer composition (% by weight) of the polymethacrylate polymer is in the following range:
0-10% acrylic acid
0-20% methacrylic acid
10-20% acrylonitrile
0-25% ethyl acrylate
0-60% butyl acrylate
20-70% methyl acrylate.

  In order to obtain sufficient penetration of the sizing agent into the yarn, the sizing bath is preferably maintained at a temperature from 30 ° C to 90 ° C. The concentration of the sizing agent in the sizing bath is preferably 2 to 20% by weight. The amount (absorption; weight increase) of the sizing agent absorbed by the yarn is preferably 2 to 30% by weight of the sizing agent (dry matter) based on the yarn (dry matter). In addition to chemically modified amylose-type potato starch, sizing solutions to be used include trace amounts of auxiliary substances conventionally used in the sizing process, such as waxes, fats, antifoams, antistatic agents, and A plasticizer can be further contained. The sizing solution may further contain other sizing agents such as polyvinyl alcohol, polymethacrylate or carboxymethylcellulose.

  When this sizing composition is used, the number of fabric yarns woven during the loom change can be increased. After weaving, the sizing material can be removed by treatment with enzymes in the usual way or by washing with detergent water.

  The compositions of the present invention can also be used in other applications, such as textile finishing, textile and paper dyeing, paper sizing, and the application of pigments or paints to fabrics and paper.

Transgenic potato plant Solanum tuberosum AM 99-2003
By using antisense, RNAi or antibody technology to target high amylose potato lines, for example, two starch branching enzymes, starch branching enzyme 1 (SBE1) and starch branching enzyme 2 (SBE2) Can produce.

  The high amylose potato line AM99-2003 is created by inhibiting starch branching enzyme activity in the parent line Dinamo. Transformation is performed using constructs of SBE1 and SBE2 in the antisense orientation driven by the gbss promoter. The nucleic acid sequence of the gbss promoter is published in EP 0 563 189.

  The pBluescript containing the 1620 bp fragment at the 3 ′ end of Sbe1 between EcoRV and SpeI is cleaved with SpeI (blunt) and XbaI and ligated with the 1243 bp SstI (blunt) and XbaI fragment at the 3 ′ end of Sbe2. Sbe2 and Sbe1 complexes are excised with EcoRV and XbaI and ligated into the binary vector pHo3.1 dissected with SmaI and XbaI. The final vector is called pHAbe12A, which refers to the nucleic acid sequence of FIG. 1 and SEQ ID NO: 1. pHo3.1 is based on pGPTVKan (Becker, D. et al., Plant Molecular Biology 20 (1992), 1195-1197), with the addition of the 987 bp gbss promoter cloned into the HindIII site of pGPTVKan, and the uidA gene with SmaI and It is deleted by SstI.

  The parental line Dinamo was transformed with the construct pHAbe12A and the transgenic line was selected as described in US Pat. No. 6,169,226. Transgenic lines were grown and analyzed for amylose production according to the method described by Morrison, W.R. and Laignelet, B., J. Cereal Sci. 1 (1983), 9-20. A transgenic line producing amylose-type starch having an amylose content of 70% or more was selected. Amylose-type starch was isolated and purified from transgenic potato plants according to general methods known in the starch industry.

For the formulation sizing (gluing) experiment, a formulation containing the amylose-type potato starch was prepared according to the following recipe.

  PHAS 2012 is a genetically modified amylose-type potato starch, 83.5% solids (water content 16.5%); measured according to Morrison, WR and Laignelet, B., J. Cereal Sci. 1 (1983), 9-20 The amylose content is 70%.

“Natural potato starch” is a regular potato that is unmodified (chemically or thermally) and contains about 20% amylose and 80% amylopectin at 84.7% solids (water content 15.3%) Starch (Emsland Staerke GmbH, Germany).
“BASF Size CE” (BASF Aktiengesellschaft, Germany) is a polyacrylate-based, 25% solids sizing agent.

  “Emsize E9” is a sizing agent based on chemically modified potato starch (degree of propoxylation 0.2 to 0.3 per repeat unit). The solid content is approximately 85% (water content 15%).

The amount of the individual components of the formulation can be varied as follows:
Depending on the performance required for weaving, the above formulation of the paste may vary in principle from 100% starch (low performance required) to 100% polymethacrylate (high performance required) . Typically, polymethacrylate-based glue is added to starch glue in a ratio of 10 (starch): 1 (polymethacrylate) to 1: 1 for a cost / performance tradeoff.

In the test comparison test, the above amylose type starch (formulation 1: PHAS 2012) is marketed based on natural potato starch (formulation 2), as well as chemically modified starch (degree of propoxylation, 0.2-0.3 per repeating unit). Tested against the best starch sizing product (formulation 3: Emsize E9). All starch ingredients were formulated with “BASF size CE”. Abrasion resistance and desizing properties were measured.

The test was conducted according to the following procedure:
Abrasion test Sizing effects are critical to the weaving characteristics of warp yarns. This effect is closely related to the wear resistance of the sized yarn. The abrasion resistance of the yarn is measured with a Zweigle abrasion tester (G552 abrasion tester, Zweigle Textilpruefmaschinen GmbH & Co.KG, Germany).

  Tighten a standard, easily replaceable abrasive paper onto a shaft that moves along the direction of the yarn. Twenty weighted yarns (cotton short fiber yarn, British count Ne 12) were passed over the shaft and polished at the same speed and pressure until the yarn was broken. The shaft is advanced forward after each stroke so that the lint in the abrasive does not affect the wear action. Read from the counter the number of polishing strokes held up to the end, and calculate the average value. The greater the number of polishes obtained, the higher the wear resistance of the yarn.

  The values obtained with the abrasion tester are only relative and these are considered in comparison to warp yarns that are not sized or sized by another formulation (in each case yarns from the same lot). Must-have.

The following results were obtained:
Wear rating (cotton yarn, Ne 12)

Desizing test
One of the most common tests for determining the effectiveness of TEGEWA starch detection pretreatment is to detect the presence of starch paste by applying an iodine / potassium iodide solution to the fabric. is there. A blue coloration indicates that the starch paste is still attached to the fabric.

  We know that in this test application, even if only 1% of the original starch paste is still attached, ie 99% is removed, the blue coloration is still visible. This is very important. However, these traces of residual glue no longer have any influence on the reaction of the pretreated fabric during dyeing or printing.

  The TEGEWA violet scale provides an improved method, which employs nine shades of color as indicated by the score. A rating of 1 indicates the least lack of desizing; 9 indicates substantially complete desizing.

Procedure Soak the fabric specimen in a 0.005 mol / l iodine solution for 1 minute. Then wash briefly with water, dab with filter paper and immediately compare with violet scale.

Preparation of iodine solution
1. Dissolve 10 g potassium iodide in 100 ml distilled water
2. Add 0.635 g iodine to this solution and dissolve.
3. Add water to make the whole 800 ml
4. Desizing characteristics to add 1000ml to the whole by adding ethanol

  Compared to conventional potato starch, the formulation with amylose-type starch having an amylose content of about 70% derived from a genetically modified potato plant produced as described in Example 1 has higher wear resistance, As well as a significant improvement in sizing performance reflecting the achievement of better desizing properties. Properties comparable to the best commercial standard samples already chemically modified and optimized were obtained with chemically unmodified amylose-type starch.

FIG. 1 is a restriction enzyme map of vector pHAbe12A.

Claims (8)

  A method of using amylose-type starch as a sizing agent for natural cotton yarn.   The method of using amylose-type starch as a sizing agent according to claim 1, characterized in that the amylose-type starch has an amylose content of at least 50%.   The method of using amylose-type starch as a sizing agent according to claim 2, characterized in that the amylose-type starch is produced by a transgenic potato plant.   Use of amylose-type starch as sizing agent according to claim 1, 2 or 3, characterized in that amylose-type starch is used in combination with other sizing agents such as polyvinyl alcohol, carboxymethylcellulose or polymethacrylate Method.   A method for sizing natural cotton yarn or a blend of cotton and polyester, characterized in that chemically unmodified amylose-type starch is used as a sizing agent.   A method for sizing natural cotton yarn, or a blend of cotton and polyester, characterized in that chemically modified amylose-type starch is used as a sizing agent.   A method for sizing natural cotton yarn or a blend of cotton and polyester according to claim 5 or 6, characterized in that the amylose-type starch is produced by a transgenic potato plant.   A method for sizing natural cotton yarn or a blend of cotton and polyester according to claim 7, characterized in that the amylose-type starch has an amylose content of at least 50%.

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